This topic has been on my mind for a long time. Maybe you too.
It never ceases to amaze me how so many people don't realize that the microphone on their phones is so sensitive that they could whisper in the midst of roaring jet engines or clanking trains, and the other party will hear them clearly.
While sitting in my children's Karate class I started sketching an obnoxious man blabbing on his phone. I tried to keep his expression passionless, as if he was having an unemotional conversion. That would keep the emphasis on his loudness. Most people who I see like this are discussing mundane things anyway. I gave him a red shirt because that color tends to invoke negative passions. The bowl haircut is based on the Three Stooges.
Actually, the mouth was much smaller. After inking and scanning it, I selected the mouth in Photoshop and used Edit=Transform to scale it 30% larger. As usual, I brought it in Illustrator, traced it and that's when the fun began with colors and shading.
I've seen lots of "text bubble" images and I thought this would be a perfect candidate. Of course, someone could delete or replace it. I just hope it makes it more marketable.